If a doctor suspects lung cancer, he or she will:

 
• Ask about your medical history  
• Perform a physical examination  
• Order specialized medical tests

As part of taking your medical history, your doctor will ask about:

 
• Whether you smoke or have smoked in the past  
• Your occupation  
• Whether you have been exposed to certain occupational hazardous substances or radiation  
• Whether you have a family history of lung cancer

Medical tests that may be performed include:

 
• Chest x-ray. This is the first and basic test that will be ordered.  
• CT scan. This is a highly specialized x-ray with computer-generated images showing slices of the lung.  
• Sputum test. This is the examination under a microscopy of a sample of the mucus you cough up. If an abnormality seen on an x-ray is suggestive of cancer, a sputum test may be ordered.  
• Biopsy. This is the removal of a sample of tissue from the body to be examined under a microscopy. A biopsy is the only way that the doctor can be absolutely certain that lung cancer is present. A physician who specializes in tissue analysis (a pathologist) can then see what type of cell is causing the growth and whether or not it is a cancerous cell.

There are different ways in which a biopsy of the lung may be obtained.

 
• Needle aspiration. While you are sedated, a doctor will insert a needle through your chest directly into the growth and, guided by x-rays, will remove a sample of tissue. Alternatively, the needle may be pushed only as far as the envelope of tissue that surrounds the lungs, removing fluid from this layer to check for the presence of cancer cells.  
• Bronchoscopy. In this procedure, which is more common than needle aspiration, a doctor passes a narrow, flexible, well-lit tube, called a bronchoscope, into your lungs while you are under sedation. The bronchoscope is passed through either your mouth or nose directly into your windpipe, and the doctor is able to see the air passages inside the lungs. The biopsy of any suspicious part of the lung can be performed through this tube.

Rarely, even after all the above medical tests, the diagnosis may still be unclear. In this case, a major operation exposing the lung may be needed. This procedure is known as a thoracotomy.